I'm going to play lizard's advocate here and give real advice.
If you want business casual, wear a blue or white button-down shirt (or a polo) with khaki pants and brown loafers. If you wear accessories, limit it to a watch. No tie.
If you want more casual, then wear a black shirt (maybe with a logo, no band shirts) with straight denim pants and neutral-colored sneakers.
Put some gel in your hair, trim your facial hair if you have any, and pop a mint.
Otherwise, just go in all plaid and claim that you're cosplaying as a TV that met a Wii Remote.